This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Obtain additional spectral information from representatives of the 100 important metabolites of Arabidopsis and populate the database. In the future, we will have a catalog containing the structures of the 10,000 or more'most-abundant smallmolecules in all human tissues. We will also be able to use this information to monitor their fluctuations in concentration in real time, as our bodies continually change. The purpose of this proposal is to take us one step closer to creating metabolomic technologies to fill this void. This proposal explores the use of stable isotope labeling of biological samples coupled with the analytical high sensitivity of mass spectrometry (MS) and the chemical selectivity of high-field NMR spectroscopy as enabling technologies for high-throughput analysis of metabolomes. We call this novel approach isotopeassisted metabolomics.